ES2900474T3 - Gear assembly, vehicle power train and electric wheel hub with the same - Google Patents

Abstract

A gear assembly comprising a rotatable input member and a rotatable output member and a gear arrangement between the input member (5) and the output member (2) selectively engageable to effect drive engagement between the gear member input and output member through at least a first torque connection (9) having a first gear ratio, a second torque connection (13) having a second gear ratio and a third torque connection (12). torque having a third gear ratio; wherein the gear arrangement includes a first coupling member (9) selectively operable to effect the first torque connection in a 1:1 ratio, a first planetary gear stage (10, 14) and a second stage (11, 15) planetary gear, and a second coupling member (13) selectively operable to effect the second torque connection and a third coupling member (12) selectively operable to effect the third torque connection respectively through one or more of planetary gear stages; and wherein the first coupling member (9) is located on a first side of the input member (5) and the first planetary gear stage, the second coupling member (13), the second planetary gear stage and the third coupling member (12) are located on a second side of the input member (5) opposite to said first side, and, characterized in that the gear assembly further comprises a rotating drive mechanism consisting of a rotating electric motor (6) for driving the input member, wherein the first coupling member is located on a first side of the rotary drive mechanism and the first planetary gear stage, the second coupling member, the second planetary gear stage and the third coupling member they are located on a second side of the rotary drive mechanism opposite said first side.

Description

DESCRIPTION

Gear assembly, vehicle power train and electric wheel hub with the same

The present invention relates to a gear assembly, in particular to a gear assembly adapted to provide at least three ratios including 1:1 in a simplified and compact manner.

Assemblies according to the invention may be useful in a variety of vehicular or other machinery applications where a simple, robust and compact gearbox is required. Gear assemblies are commonly used in vehicles where it is desired to drive a wheel or axle at a rotational speed other than the revolutions of an engine. Assemblies in accordance with the invention may find particular application in a gear system for an electric hub drive, and applications of the invention are discussed herein in that context by way of example, although the invention is not limited to such applications. .

Electric hub drives, or hub-mounted electric drive units (HMEDs) are finding increasing use in vehicles where it is advantageous for the wheels to be driven independently. Applications include, for example, large vehicles and vehicles adapted for use on difficult and, for example, steep or uneven terrain. HMED units are finding increasing use in hybrid vehicles. HMED units are finding increasing use on military vehicles especially for rough terrain use.

Each wheel is provided with a hub-mounted electric drive assembly typically comprising a housing containing an electric motor, and a power train including a drive shaft, disposed within a suitable hub-mounted housing. An output shaft of the hub drive drives the wheel. The hub drive assembly must fit within the space available within the diameter and overall width of the tire and wheel rim assembly.

The use of individual hub-mounted electric drive units eliminates the need for conventional transmission and drive shafts and offers increased vehicle capabilities through improvements in vehicle performance, fuel economy, design configuration, increased stealth capability and reduced lifetime costs.

The requirements of a drive for an electric hub are such that it must have a large torque range and a large speed range, as well as being compact. A multi-speed gear change mechanism is desirable to facilitate this. Higher gear ratios can be used to provide higher torques at lower speeds and lower gear ratios to allow higher speeds (with low torque output available).

In EP1692416 there is disclosed a two speed gear assembly including a 1:1 ratio and planetary gear set reduction which can be selectively engaged by means of a single compact dog clutch arrangement. An adaptation of this mechanism to provide a third ratio, for example by providing a second planetary gear set in series with the first could significantly complicate the required dog clutch arrangement. For example, a dog clutch for high gear selection may be provided within a tubular shaft between the motor rotor and the intermediate stage sun gear with radial pins and splines for actuation.

A simpler mechanism, and in particular one that remains compact at least in the axial direction, is desirable for application in, for example, electric hub drives.

US2012/129646 discloses a continuously variable transmission for a vehicle.

In accordance with the invention in a first aspect, a gear assembly comprises a rotatable input member and a rotatable output member and a gear arrangement between the input member and the output member selectively engageable to effect drive coupling between them. the input member and the output member through at least a first torque connection having a first gear ratio, a second torque connection having a second gear ratio, and a third torque connection having a third gear ratio gear; wherein the gear arrangement includes a first coupling member selectively operable to effect the first torque connection in a 1:1 ratio, a first planetary gear stage and a second planetary gear stage, and a second selectively operable coupling member to effect the second torque connection and a third coupling member selectively operable to effect the third torque connection respectively through one or more of the planetary gear stages; and wherein the first coupling member is located on a first side of the input member and the first planetary gear stage, the second coupling member, the second planetary gear stage and the third coupling member are located on a second side of the input member opposite said first side, and characterized in that the gear assembly further comprises a rotating drive mechanism consisting of a rotating electric motor to drive the input member, wherein the The first coupling member is located on a first side of the rotary drive mechanism and the first stage planetary gear, the second coupling member, the second stage planetary gear and the third coupling member are located on a second side of the rotary drive mechanism. rotary drive opposite said first side.

More conveniently, to achieve the three different desired ratios, the second torque connection is made through one of the planetary gear stages and, for example, the first planetary gear stage and the third torque connection is made through the first planetary gear stage and the second planetary gear stage in series.

Thus, in this preferred case, the gear arrangement includes a first coupling member selectively operable to effect drive engagement between the input member and the output member in a first 1:1 ratio, a first planetary gear stage, and a second coupling member selectively operable to effect drive coupling between the input member and the output member through the first planetary gear stage, and a second planetary gear stage and a third coupling member selectively operable to effect driving coupling between the input member and the output member through the first planetary gear stage and the second planetary gear stage in series; wherein the first coupling member is located on a first side of the input member and the first planetary gear stage, the second coupling member, the second planetary gear stage and the third coupling member are located on a second side of the input member opposite said first side.

The invention is clearly characterized by the positioning of the first coupling member which effects a driving coupling between the input member and the output member in a 1:1 relationship on the opposite side of the input member from the two sets of planetary gears. , and in particular, on the opposite side of the rotary drive mechanism of the two sets of planetary gears.

This allows a second planetary gear set to be added in series to the first, for example to exploit and develop the embodied principles and advantages offered by the two speed single planetary stage system of EP1692416, but in a way that avoids the particular difficulties that would arise if the first coupling member were more conventionally mounted on the same side as the planetary gear sets. Such an arrangement presents particular difficulties with multiple planetary gear systems, as a complex mechanism is then required to enable the 1:1 ratio coupling member to be driven via the rotating output shaft. This problem is avoided by providing the 1:1 ratio coupling member on the other side of the input shaft/drive mechanism.

The first torque connection is effected by a first coupling member to provide a 1:1 gear ratio (as a ratio of input member: output member angular velocity). Although this may be referred to here for convenience as one of the three speeds of the gear arrangement, this torque connection is gearless.

For example, in a convenient embodiment, the first coupling member comprises a selectively engageable coupling means that can be coupled to effect drive coupling directly between the input member and the output member.

Preferably, the first coupling member includes a first dog clutch arrangement. Preferably, the dog clutch arrangement comprises an annular dog ring.

Preferably, the first coupling member is provided with a first actuator to effect its selective coupling and uncoupling. Preferably, the first actuator comprises a first selector bushing such as a dog bushing driven for axial movement relative to the output member to effect selective engagement of the first coupling member for example being the first dog clutch. Preferably the first actuator further comprises a shift fork for effecting axial movement of the first selector bushing.

The second and third torque connections are provided by the arrangement of the first planetary gear stage and the second planetary gear stage on an opposite side of the input member, and consequently, on an opposite side of a rotating drive mechanism that drives said input member.

Each planetary gear stage typically comprises a sun gear, at least one planetary gear, and more usually a set of planetary gears circumferentially distributed around and meshed with the sun gear and supported by a common planetary carrier coaxially located with the sun gear. and a ring meshing with the planet gear(s), a first of said sun gear, planet carrier, or ring configured to be driven on an input side of the gear stage, a second of said sun gear, planetary carrier, or ring configured to rotate on one output side of the gear stage.

Each sun gear, planet gear and ring gear is adapted to engage in mated engagement with its counterparts to effect mated rotation in a familiar manner. Typically, each gear has a flat gear body with a plurality of teeth of identical size and evenly spaced around the circumference. For compactness and torque balance a plurality of identical planet gears distributed around the sun gear are preferably provided. For example, three to six planet gears are provided in association with a sun gear.

In a preferred arrangement, each planetary gear stage is configured as a reduction gear in which the sun gear is arranged to be driven on an input side of the gear stage, the planetary carrier is arranged to rotate on an output side of the gear and the ring is held non-rotatably.

In a preferred arrangement, the two planetary gear stages are configured to provide a second torque connection having an intermediate gear ratio greater than 1:1 but less than that of the third torque connection, and a third torque connection having a gear ratio greater than 1:1 and greater than that of the second torque connection.

Conveniently, this is achieved in that the second torque connection is via the first planetary gear stage and the third torque connection is via the first planetary gear stage and the second planetary gear stage in series.

Preferably, the first and second planetary gear stages are identical.

Preferably, the first and second planetary gear stages are arranged coaxially and adjacent to each other.

Preferably, the first and second planetary gear stages are provided with a common ring.

Preferably, the first and second planetary gear stages are configured to produce a gear ratio of between 2.5:1 and 3:1 and, for example, a ratio of about 2.7:1.

This reduction ratio is ideal as it fits the requirements of typical traction motors, which can easily be made to deliver constant power over a 3:1 speed range. Two approximately 2.7:1 gear stages arranged in series give a mechanical ratio spread of approximately 7:1 and combined with the drive motor speed range gives an overall range of approximately 20:1.

The second and third torque connections are provided through the arrangement of the first planetary gear stage and the second planetary gear stage. In the preferred case, the second torque connection is made by creating a drive coupling between the input member and the output member through the first planetary gear stage and the third torque connection is made by creating a driving coupling between the input member and the output member through the first planetary gear stage and the second planetary gear stage in series.

The second torque connection is made by the second coupling member. Preferably, the second coupling member comprises a selectively engageable coupling means for effecting drive coupling between the input member and the output member through the first planetary gear stage. Preferably, the second coupling member includes a second dog clutch arrangement. Preferably, the dog clutch arrangement comprises an annular dog ring.

The third torque connection is made by the second coupling member. Preferably, the third coupling member comprises selectively engageable coupling means which can be coupled to effect drive coupling between the input member and the output member through the first and second stages of planetary gearing in series. Preferably, the third coupling member includes a third dog clutch arrangement. Preferably, the dog clutch arrangement comprises an annular dog ring.

Preferably, the second coupling member is provided with an actuator to effect its selective coupling and uncoupling. Preferably, the third coupling member is provided with an actuator to effect its selective coupling and uncoupling. Conveniently a second actuator is provided to effect selective engagement of one, the other or neither of the second and third engagement members. For example, the second actuator comprises a second selector bushing, such as a second dog bushing supported for axial movement relative to the output member to effect selective engagement of one, the other, or neither of the second and third coupling members, being for example the second and third dog clutches. Preferably the second actuator further comprises a shift fork for effecting axial movement of the second selector bushing.

The input member is, for example, an input shaft directly mechanically coupled or integrally formed with a motor rotor of the rotary drive mechanism.

The output member transmits the rotary output drive to a driven system, for example to a vehicle drive transmission system. The output member is, for example, an output shaft directly mechanically coupled or integrally formed with a drive shaft of the system to be driven.

Preferably, the input member is disposed coaxially with and about the output member. Preferably, the output member extends axially beyond the input member on either side, the first coupling means being arranged in association with and for example around said axial extension on a first side, and the first planetary gear stage, the second coupling member, the second planetary gear stage and the third coupling member are arranged in association with and for example around said axial extension on a second side.

For example, the input member comprises a motor rotor of the rotary electric motor, the output member comprises a drive shaft, and the motor rotor is an annular rotor disposed coaxially with and about the drive shaft, the drive shaft it extends axially beyond the annular motor rotor on each side.

Preferably, the gear assembly provides a three speed drive configuration. The gear assembly can be further modified to provide more speeds.

In another aspect, the present invention also provides a vehicle power train that includes the gear assembly described above.

In another aspect, the present invention also provides an electrical drive of the wheel hub containing the gear assembly described above.

The present invention will now be described by way of example only, and with reference to the following drawing, in which: Figure 1 is a schematic cross-section of a gear assembly in accordance with one embodiment of the present invention.

The embodiment shows a drive configuration that provides three gear ratios including 1:1. An electric rotary drive traction motor rotor is coupled to an output drive shaft, either directly, through a planetary gear reduction, or through two planetary gear reductions in series.

In order to address the issues raised above regarding direct coupling drive accessibility, the present invention takes the approach of splitting the gear assembly and placing the direct coupling on a first side of the traction motor and gear reductions. planetary gears on a second side of the traction motor. This drive configuration, which has the high coupling system on one side of the traction motor and the planetary gears and mid/low coupling system on the other side of the motor, allows for a simplified mechanism.

Figure 1 is a schematic cross-section of a drive configuration generally denoted 1 including a gear assembly in accordance with one embodiment of the present invention. The gear assembly includes a gear arrangement that is adapted to engage with and provide a rotary output drive to a drive shaft 2 . Rotating input is provided from a rotating electric traction motor through a motor rotor 5 driven by an annular stator 6. The motor rotor 5 annularly surrounds the drive shaft 2 which extends axially beyond it on both sides. The gear arrangement is clearly characterized by the arrangement of a 1:1 rotor to drive shaft coupling means to engage after a first axial extension on a first side of the traction motor, and the arrangement of a planetary gear system which offers two further ratios, and in particular two reduction ratios, in such a second axial extension on a second side of the traction motor. The high, mid, and low dog clutches effect selective engagement of all three ratios, all shown disengaged in Figure 1.

The first 1:1 coupling means includes a first high dog clutch 9 provided with a set of selectively engageable and disengageable dogs for effecting a first torque connection between the motor rotor and the drive shaft in a 1:1 relationship. Selective coupling and uncoupling is effected by the axial movement of a first selector bushing 3 . The first selector bushing 3 has an annular body surrounding the shaft 2 and is provided on the left side (as shown) with a set of dogs structured complementary to the dogs of the first dog clutch. The selector bushing 4 is supported for axial movement relative to the drive shaft by means of a splined connection 7 so that the bushing and shaft must rotate together but the bushing is able to slide axially on the shaft back and forth. from the position illustrated in Figure 1. The axial movement is effected by an operator using the shift fork 8. To couple the 1:1 ratio the first selector bushing 4 moves to the left (as shown) and a torque transfer engagement is effected between the high dog clutch 9 and the first selector bushing 3 so that the input of the motor rotor is coupled to the output of the drive shaft in a 1:1 ratio.

The other two gear ratios, respectively a mid gear and a low gear, are provided by the selective engagement of the planetary gear system arranged on the other side of the traction motor.

The first and second stages of planet gears are arranged in series and respectively comprise a first sun gear 10 meshed with a first set 14 of planet gears and a second sun gear 11 meshed with a second set 15 of planet gears, with a gear 16 of common ring. Both gear stages are arranged as reduction gears, with the sun gear as input and the planetary carrier as output, and with the common ring gear non-rotatably supported.

A second mid dog clutch 13 and a third low dog clutch 12, each provided with a set of selectively engageable and disengageable dogs, are provided to respectively effect a second torque connection between the engine rotor and drive shaft. drive and a third second torque connection between the motor rotor and the drive shaft in respective second and third ratios. Selective engagement and disengagement to effect a mid gear or low gear engagement is effected by axial movement of a second selector bushing 17 .

The second selector bushing 17 has an annular body that surrounds the shaft 2 and is provided on both sides with a set of dogs complementary structured with dogs of a respective dog clutch. The selector bushing 17 is supported for axial movement relative to the drive shaft by means of a splined connection 18 so that the bushing and shaft rotate together but the bushing is able to slide axially on the shaft from side to side. from the position illustrated in Figure 1, in which no dog clutch is engaged. The axial movement is effected by an operator via the shift fork 19. To engage the middle gear the second selector bushing 17 is moved to the right (as shown) and a torque transfer engagement is effected between the intermediate dog clutch 13 and the complementary dogs on the second selector bushing 17, so that the motor rotor input is coupled to the drive shaft output only through the first planetary gear stage. To engage low gear the second selector bushing 17 is moved to the left (as shown) and a torque transfer engagement is effected between the low dog clutch 12 and the complementary dogs on the second selector bushing 17 so that the input of the motor rotor is coupled to the output of the drive shaft through the first stage planetary gear and the second stage planetary gear successively in series.

Thus, the system provides three selectable ratios. Using the above configuration the high 9, medium 12 and low 13 dog clutches are used to couple the rotor 5 to the drive shaft 2, respectively, directly, through one planetary gear reduction or through two planetary gear reductions in Serie. As the lowest gearing is achieved in the embodiment using the two reduction stages in series, the ratios of those two stages need not be different and are preferably identical, although they may differ if desired, and other gear arrangements could be considered. planetary gears to get the medium and low gears.

Preferably, the two stages of planetary gears are configured with relatively low reduction ratios, eg, about 2.7:1 per stage. Planetary gears are correspondingly small compared to the sun gear. Two gear stages of approximately 2.7:1 per stage give a mechanical ratio of approximately 7:1 when the two stages are combined in series, which combined with a typical range of electric traction motors results in a range of approximately 20:1 .

The use of a planetary gear reduction with a ratio of approximately 2.7:1 with relatively small planetary gears and large sun gears is further advantageous as this allows the interior space of the sun gears to accommodate dog clutch components for meshing the sun gears. mid and low gear ranges.

The drive configuration of this embodiment, by placing the high engagement dog clutch system on one side of the traction motor and the planetary gears and medium/low engagement dog clutch system on the other side of the motor allows for a simplified mechanism. In contrast, keeping the high dog clutch on the same side of the engine as the two-stage planetary gears would require a more complex arrangement, for example locating a dog inside a splined tubular traction motor output shaft. radials and pins to allow actuation.

These and other preferred embodiments of the present invention will become apparent from the appended claims.

Claims (15)

1. A gear assembly comprising a rotatable input member and a rotatable output member and a gear arrangement between the input member (5) and the output member (2) selectively engageable to effect drive coupling between the input member and the output member through at least a first torque connection (9) having a first gear ratio, a second torque connection (13) having a second gear ratio, and a third torque connection (12). ) of torque having a third gear ratio; wherein the gear arrangement includes a first coupling member (9) selectively operable to effect the first torque connection in a 1:1 ratio, a first planetary gear stage (10, 14) and a second stage (11, 15) of planetary gear, and a second coupling member (13) selectively operable to effect the second torque connection and a third coupling member (12) selectively operable to effect the third torque connection respectively through one or more of planetary gear stages; and wherein the first coupling member (9) is located on a first side of the input member (5) and the first planetary gear stage, the second coupling member (13), the second planetary gear stage and the third coupling member (12) are located on a second side of the input member (5) opposite said first side, and, characterized in that the gear assembly further comprises a rotary drive mechanism consisting of a rotary electric motor (6) for driving the input member, wherein the first coupling member is located on a first side of the rotary drive mechanism and the first planetary gear stage, the second coupling member, the second planetary gear stage and the third coupling member are located on a second side of the rotating drive mechanism opposite said first side. 2. The gear assembly of claim 1 wherein the planetary gear stages are arranged such that the second torque connection (13) is effected through engagement of the first planetary gear stage (10, 14) and the third torque connection (12) is effected through the coupling of the first stage (10, 14) planetary gear and the second stage (11, 15) planetary gear in series. 3. The gear assembly of claim 1 or claim 2 wherein the first coupling member (9) is selectively operable to effect drive coupling between the input member (5) and the output member (2) in ratio 1:1, the first planetary gear stage (10, 14) and the second coupling member (13) are selectively operable to effect drive coupling between the input member and the output member through the first planetary gear stage, and the second planetary gear stage (11, 15) and the third coupling member (12) are selectively operable to effect driving coupling between the input member and the output member through the first planetary gear stage and the second planetary gear stage in series. 4. The gear assembly of any preceding claim wherein the first coupling member (9) comprises a selectively engageable coupling means for effecting a driving coupling directly between the input member (5) and the output member (2). the first coupling member (9) being optionally provided with an actuator (8) to effect its selective coupling and uncoupling. 5. The gear assembly of claim 4 wherein the first coupling member (9) includes a first dog clutch (9), and is optionally provided with a selector bushing (4) supported for axial movement relative to the output member (2) for effecting selective engagement with the first dog clutch (9). 6. The gear assembly of any preceding claim wherein each planetary gear stage comprises a sun gear (10), a set of planetary gears (14) distributed laterally around and meshed with the sun gear and supported by a common planetary carrier located coaxially with the sun gear, and a ring (16) that meshes with the planet gears. 7. The gear assembly of claim 6 wherein each planetary gear stage is configured as a reduction gear in which the sun gear (10) is arranged to be driven on an input side of the gear stage, the planetary carrier is arranged to rotate on an output side of the gear and the ring (16) is non-rotatably supported. 8. The gear assembly of claim 6 or 7 wherein the first and second planetary gear stages are identical. The gear assembly of one of claims 6 to 8, wherein the first and second planetary gear stages are provided with a common ring (16). 10. The gear assembly of any preceding claim wherein each planetary gear stage is configured to produce a gear ratio of between 2.5:1 and 3:1. 11. The gear assembly of any preceding claim wherein the second coupling member (13) comprises selectively engageable coupling means arranged to be coupled to effect drive coupling between the input member and the output member through the first planetary gear stage, and/or the third coupling member (12) comprises selectively engageable coupling means arranged to be coupled to effect drive coupling between the input member and the output member through the first planetary gear stage and the second planetary gear stage in series; and optionally, wherein the second and/or third coupling member includes a dog clutch arrangement. The gear assembly of any preceding claim wherein the input member comprises an input shaft (5) directly mechanically coupled or integrally formed with a rotary drive motor rotor (5). 13. The gear assembly of claims 1 to 11, wherein the input member is disposed coaxially with and about the output member, the output member extending axially beyond the input member on each side, the former being coupling means arranged in association with said axial extension on a first side, and the first planetary gear stage, the second coupling member, the second planetary gear stage and the third coupling member arranged in association with said axial extension on a second side. 14. The gear assembly of claim 13, wherein the input member comprises a motor rotor (5) of the rotary electric motor (6), the output member comprises a drive shaft (2), and the rotor ( 5) of the motor is an annular rotor arranged coaxially with and around the drive shaft (2). the drive shaft extends axially beyond the annular motor rotor on each side. 15. A vehicle power train or electric wheel hub drive including the gear assembly of any preceding claim.